Process of making oxalates.



UNITED STATE PATENT @FFTUE.

ALBERT HEMPEL, 0F LEIPZIG-OETZSCH,GERMANY.

PROCESS OF MAKING OXALATES.

No Drawing.

To all whom it may concern:

Be it known that I, ALBERT HEMFEL, doctor of philosophy and a chemical engineer, a citizen of the Kingdom of Saxony, in the German Empire, residing at Leipzig-Oetzsch, in the Kingdom of Saxony, German. Empire, have invented certain new and useful Improvements in Processes of Making Oxalates; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to Which it appertains to make and use the same.

This invention relates to an improved process of making oxalates.

According to the oxalate process hitherto employed a formate is mixed with neutral substances and this mixture is then heated.

The conversion of formates into oxalates can also be obtained according to the process described in my'Brit-ish Patent No. 3429, of Februaryl5, 1908, by which the formate is heated at a .pressure higher than that of the atmosphere from'QOO" up to a maximum of 440 C. Without any indifferent substances being added.

According to my United States Patent No, 1,017 ,261 formate is produced by adding causticsoda in successive quantities to carbon monoxid under an increased pressure and ata temperature below and above 200 C., With the carbon monoxid in excess; the formats reaction will be the quicker and more favorable, the larger the quantity of gas escaping therefrom. This, however, would mean losses in carbon inonoxid gas, which is contained up to 30 per cent. in producer-gas, as the gas escaping from the formate autoclavcs 'is' poor in carbon 1no-' noxid andv rich in nitrogen and cannot be used for the further production of formats. The present invention allows of fully utilizing this surplus gas obtained by the production of form-ate according to my United States Patent No. 1,017,261 and applying this gas for converting formate into oxalate. As stated before, this gas still contains large quantities of carbon IHOIIOXltl. It escapes Specification of Letters Patent. Patented Aug, 319, 1913,, Application filed February 24, 1912. Serial No. 679,683. i

from the-formateautoclave at a pressure of from 610 atmospheres and ata tempera;- ture offrom 150200 C. lVhen this gas is conducte over finished for-mate heated to 300-4-it0 0., the formats will be much more rapidly converted into oxalate and above all in an absolutely safe and cheaper manner. The high temperature and high advantage. Also the contents of carbon monoxid in this gas can be utilized, as-any free alkali still contained in the formats will be subsequently c'onverted by the car-- bon monoxid first-into formate and then into'oxalate. Therefore there will be no loss of expensive caustic alkali andthe resulting oxalate is therefore, being free from caustic. alkali, of a much higher value. As the carbon monoxid contained in this gas will subsequently have converted all free caustic alkali contained in the formate, into forniate, the conversion of formats into oxalate Will be almost quantitatively complete and Without any decomposition.

pressure of this gas is favorable to the "or r matron of oxalate and can be utilized to According to the present process the hydrogen liberated during the formation of oxalate proceeding under pressure Will be immediately'removed in state 'nascendi by the formate Waste-gas passing under pressure through the oxalate apparatus. 'The generation of hydrogen Will-be gradual, and a sudden. generationof hydrogen and ex plosions caused thereby are rendered impos v sible according to the present process.

The novel technical efiects of the present process have never been attained by any known oxalate process. I v a y This advantageous process permits-that the formation of formate and oxalate is car-- ried out in one and the same apparatus.

l/Vhen according'to the United States patent referred to caustic soda has been converted into fcrmate (the completion of the reaction being observed by a drop of the temperature) the formats produced is gradually heated to more than 3GO-MO C. under continuation of the supply of carbon monoxid,

or while another aste-gas, escaping from a ture of fonnate from carbon lnonoxid and 10 not yutcolnplelml formate autoclave, is caustic alkali. passed tlnouglitlie some. In testimony, that I claim the foregoing I claim: as my invention, I have signed my name in The process herein ios ribed of making presence of two subscribing Witnesses.

or -alums, which consisnn in heating formates ALBERT HEMPEL. gradually to a temperature of from 360 l/vi tnesses: 440 C. While passing through it the hot RUDOLPH FRIOKE,

waste-gas which is obtained in the manufac- FRITZ GUINING. 

